Coordination polymers derived from silver salts and an aliphatic N,O ligand

Cocrystallization of silver salts with the polyfunctional, conformationally flexible ligand N-(2-cyanoethyl)-β-alanine (cea) yielded three different coordination polymers, namely a rare example of a compound containing helical chains assembled into an infinite 2D array, [Ag₄(cea^-)₂(NO₃)]BF₄ (1), a 3D channel structure, [Ag₄(cea)₂(H₂O)(CF₃SO ₃)₄] (2), and an unprecedented structure comprising 1D polymeric anions sandwiched between the loops of a cationic pleated sheet, [Ag₃(cea)₂(NO₃)][Ag₂(NO ₃)₃]NO₃ (3). In 2 and 3 the central amino nitrogen of cea is protonated and non-coordinating so that the ligand has two metal binding sites separated by a five-membered aliphatic linker and a central hydrogen bond donating site. In the case of 2 this gives rise to 44-membered macrometallacyclic subunits that generate large rhombic channels hosting the counterions.